This invention relates generally to devices for use in the diagnostic analysis of liquid specimens through binding assays, and, more particularly, to devices of this type for use in multiple simultaneous testing of such liquid specimens.
One device of this particular type is disclosed in a copending and commonly-assigned application for U.S. patent Ser. No. 308,935, filed on Oct. 5, 1981, in the name of Vincent A. Marinkovich now issued as U.S. Pat. No. 4,459,360, entitled "Multiple-Component Binding Assay System and Method of Making and Using It." The application discloses a diagnostic kit that includes a support and a plurality of cotton filaments secured to the support in spaced relationship, for simultaneous contact with a liquid test sample. Each filament is coated with a unique binding assay component, such as an allergen, that is covalently bound through cyanogen halide induced linkages.
In use, the support and filaments are incubated with a liquid specimen, and the amount of multiple biological agents interacting with the binding assay components coated on the filaments is determined. When screening for the presence of multiple allergen-specific IgE class antibodies in a liquid sample, the device is incubated with the test sample and then, after washing, incubated with a solution containing labeled antibodies against the IgE class antibodies that have bound to the filaments. The filaments are then analyzed to determine the presence of the labeled antibodies. If the labeled antibodies are labeled with a radioactive tracer, such as .sup.125 I, this analysis can be accomplished using a gamma counter. Alternatively, the analysis can be accomplished by placing the filaments adjacent to photographic film for exposure and by then measuring the degree of exposure.
Although the device described above has performed well in allergy screening, it is not believed to be entirely satisfactory. One reason for this is that the allergen-coated filaments are exposed during handling, which might have an effect on the outcome of the testing. In addition, there is no guarantee that each device will always be used with a specific amount of the liquid specimen, which might affect the repeatability of the testing. Moreover, when used with radioactively-labeled antibodies, such as .sup.125 I, the filaments themselves can become radioactive, thereby making subsequent handling of the devices somewhat hazardous. Still another drawback to the device described above is that a strong reaction on one of the filaments can mask or otherwise interfere with the measuring of the reactions on adjacent filaments.
It should be appreciated from the foregoing that there still is a need for a device for use in the diagnostic analysis of liquid specimens using binding assays, that can be used for multiple simultaneous testing of the sample and that is relatively inexpensive to manufacture and convenient and safe to use. The present invention fulfills this need.